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ß-Glucan:
Zymosan—the beginning of a long,
complex and fascinating research
In
1900, von Dungern observed that adding yeast to blood serum
inactivated the complement system.The complement system
known today consists of 20 proteins which are found in greatest
concentration in the plasma, precursors for enzymes which
can be activated to promote destruction of foreign cells.They
also induce inflammation through which the action of phagocytic
cells is enhanced to engulf and digest foreign matters.In
1914, Coca found that the inactivation was due to
the removal of the component C´3 of the complement
system.A more effective inhibitor „Zymin“ was found by Whitehead,
Gorden and Wormal by extracting baker’s yeast with
alcohol and ether. Pillemer and Ecker developed zymosan,
an insoluble yeast fraction by boiling yeast in alkaline
pH, digestion with trypsin and subsequently washed with
water and alcohol, which was more potent in the inactivation
of complement component C´3. With zymosan, Pillemer
was able to isolate a new protein of the complement system
involved in the non-specific immunity which he named as
´properdin´ - factor P as we know today.
With
this discovery, a series of studies on host-defense system
began with the help of zymosan and later other polysaccharides.
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ß-glucans
and their functional mechanisms
Earlier studies using zymosan
generated often contradictory results because
the preparations were not unique and the compositions
were not characterized in depth. Basically,
zymosan preparations were composed
of glucan, mannan,
protein, chitin, lipid and ash.
The percentage of each component
varied with the preparation methods.
With the advance of
modern analytical and biological methods,
several key functional effects related to
zymosan, could be ascribed to its major component
ß-glucan
with -1,3/ß-1,6-linkage.
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Major
research areas were:
-Activation
of phagocytosis,
-Resistance to infection
-Cancer
-Influence of cholesterol
synthesis
-Stress
-Survival after irradiation
A more detailed and
comprehensive review on zymosan was given by Fizpatrick
and DiCarlo
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